1. Field of the Invention
The present invention generally relates to an apparatus used to fabricate semiconductor devices. More specifically, the present invention generally relates to an apparatus used to dry semiconductor substrates.
A claim of priority is made to Korean Patent Application No. 2004-52647, filed on Jul. 7, 2004, the contents of which is herein incorporated by reference.
2. Description of the Related Art
Residual chemicals, small particles, and contaminants generated on semiconductor wafers during a fabrication process must be removed using one or more cleaning processes. The cleaning processes include a chemical process, a rinsing process, and a drying process. The chemical process is performed to etch and peel contaminants off wafers by a reaction with a chemical solution such as fluorine. The rinsing process is performed to clean the chemically-treated semiconductor wafers with deionized water. The drying process is performed to dry the semiconductor wafers.
Conventionally, as disclosed for example in U.S. Pat. No. 5,829,156, a spin dryer is used to perform the drying process. However, as integrated circuits become more complicated, the use of a spin dryer becomes problematic. This is because the spin dryer employees centrifugal force. Therefore, it is very difficult to completely remove minute water droplets remaining on a wafer, and a wafer may inadvertently become contaminated by eddies generated by the high-rotational forces applied to the wafer.
To overcome these problems, semiconductor substrates have been dried using organic compounds such as isopropyl alcohol. Typically a vapor dryer, a Marangoni dryer, and a spray dryer have been used with the organic compounds. When using the vapor dryer, isopropyl alcohol (IPA) is heated inside a process chamber, and then resulting IPA vapors displace deionized water adhering to a surface of wafers. In a Marangoni dryer, wafers are dried by a Marangoni effect taking advantage of the low surface tension of IPA vapors. In a spray dryer, externally generated IPA vapors are injected in a process chamber, and then the IPA vapors displace deionized water adhering to a wafer surface. Other conventional methods and systems are disclosed in U.S. Pat. No. 5,054,210 and Japanese Laid-Open Publication No. 10-335299.
Most drying systems use organic compounds, e.g., IPA vapors, as a drying source to dry the wafers. However, the conventional systems do not have any means to precisely detect and control the flow of IPA vapors into, and the flow of IPA vapors within a process chamber.